Force pump



July 17, 1923. 1.462.308

M. W. TUTT FORCE PUMP Filed July 25 1922 2 Sheets-Sheet l Inventor Am @W/ mm July 17, 1923.

M. W. TUTT FORCE P UMP Filed July 25 1922 2 Sheets-Sheet 3 Patented July 17, 1923.

UNITED BURD ENGINEERING COB 11 i;

F F l C E Ff. ZPUl-IYIP.

Application filed July 25, 1522.

To all whom it may concern:

Be it known that l, Monrseun ll inrinur Tn'r'r, a subject of the King of Great Britain, residing at St. Benet Chambers, Fenchurch Street, London, England, have invented. new and useful Improvements in Force E umps, of which the following is a specification.

This invention relates to force-pumps for compressing air or gas and feeding or displacing liquids, of the kind wherein the pump body or cylinder is provided with two pistons or plungers differentially movable in the same direction, between which the charge is compressed, the rod of one plunger extend-- ing through the rod of the other plunger, the object of the invention being to provide an improved pump of this type in which the usual suction and hack-pressure or non-re turn valves are dispenser with According to the invention the improved. pump comprises a cylinder having inlet and outlet ports and a pair of plungers designed to be reciprocated in the said cylinder, the suction and compression space being provided between the said plungers. For this purpose the outer or upper plunger is maintained stationary for a portion, say one third, of each stroke whilst the lower or inner plunger is moving to draw in a charge through the inlet port. The two plungers then move together for the remaining portion of the stroke which brings the induced charge opposite the outlet port. On the re turn stroke the outer or upper plunger is again held stationary for the first portion of the stroke, whilst the lower or inner plunger is drawn towards it to expel the charge through the outlet port after which the two plungers move together tor the remaining portion of the stroke, when the operation begins de novo.

To operate the plungers, l advantageously make use of an arrangement in which the rod of the inner or lower plunger is reciprocated by a cross-head actuated by a crank on crank shaft, and according to my present vention I also provide means for not only reciprocating the outer plunger, but varying the period during which the outer or temporarily stationary plunger is he stationary, so that the amount or char which is drawn in between. the two plun and is discharged through the outlet is orr spondingly varied, any residual charge b lng subsequently forced out through the inlet Serial No. 577,405.

port. In a suitable way of carrying out the invention, I employ a base plate upon which two superposed cam plates are centrally pivoted that each can be independently adjusted in a rotary direction thereon, suitable means, such as concentric slots in the cam pl: and securing bolts attached to the base plat-c, and extending through said slots, be ing proyided tor securing the cam plates in the position into which they are adjusted. Tiiese cam plates each carry a cam surface which bears against roller attached to the upper or outer plunger, thereby holding the s l plunger stationary for the period re c .d. The outward or inward movement o the outer or upper plunger is positively etiected by an GKiJQHSlOIl piece on the crosslead while the return movement thereof is eli'ected by the inner or lower plunger.

The pump may be either of the single acting oe oi the tandem type, or in the term of two sets of tandem pumps, placed side by side, or two sets of tour pumps may arranged one oncach side of the center line of the crank shaft, all the plungers being controlled by a single crank or cam.

My present invention is an improvement upon the form of pump illustrated in my former U. S. l atent #1A13j205, dated April 18, 1922.

To one. lo the invention to be fully understood, will describe it by reference to the accompanying drawings, in which 1 is a sectional elevation of a "forcepump having the improvements applied thereto, and

2 is view similar to Fig. 1, but showing the cam fates adjusted to expel a quantity of the charge through the ch ,e outlet.

0: indicates the upper or outer plunger. 7) the lower or inner plunger, and c, the cylinder in which the said plungers are reciprocated. 6 ant are respectively, the inlet and exhaust ports ot the cylinder. g is a rod of the inner or lower plunger, Z), which extends .i' through the plunger (4. 7i, iliustrated in do d lines, is the cross-head to which the outer end oi": the rod 9, is attached, and which is reciprocated by means of a sliding block, 71, moving in a. slot, If, in the crosssad, the block being carried by crank pin, off the crank shatt, i, 71 is the extension piece provided on the cross-head, h, for positively actuating the plunger a. The plunger,

a, is prevented from rotating in the cylinder by means of a longitudinal groove, 9 engaged by a set screw, 9, in the cylinder wall, and is a roller attached to the plunger, a, and coacting with the cam surfaces hereinafter described.

in is a base plate or disc, keyed upon the crank shaft 2', and Z and mare, respectively, the superposed cam plates, which are centrally pivoted upon the base plate so that they can be adjusted in a rotary direct-ion independently with respect thereto, the cam plates Z and m carrying the cams Z" and m respectively. 0 indicates a concentric slot formed in the cam plate, Z, and 0 is a simi lar slot formed in the cam plate m, said slots being engaged by bolts, 29 and p, respectively which are provided with looking nuts to retain the cam plates in the positions to which they are adjusted.

Figure 1 shows the cam plates Z and m set for the full capacity of the pump, the two plungers meeting at the dis-barge end. of the stroke at the same moment that the cam roller is released from the cam, the whole of the charge between the two plungers thus having been expelled through the outlet port 7.

The pump operates as follows, that is to say, at the beginning of a stroke, the lnner end of the plunger, a, is approximately coincident with the outer end of the inlet port, 6, and the plunger, Z), is in contact with the plunger, (4. In this position of the parts, the roller, j, is just in contact with the inner surface of the cam, on. As the crank shaft rotates in the direction of the arrow, the plunger, 6, will be moved. inwardly, the plunger, a, being held stationary by the cam, m until the latter passes out of contact with the roller, during which period the move ment of the plunger, Z), has drawn a charge into the space between the plungers. For the remaining portion of the stroke, the two plungers move together, the inlet port being completely closed by the plunger, a. The continued rotation of the crank shaft then moves the plunger, Z), upwardly while the plunger, a, is held stationary by the engage ment of the roller, j, with the exterior of the cam, Z, thereby expelling the fluid between the two plungers through the outlet port. This relative movement continues with this adjustment of the cams until the plunger, 6, contacts with the inner end of the plunger, at which point the cam, Z, leaves the roller, 7', and for the remainingportion of the stroke, the two plungers move together until the cam on again engages the roller j, when the operation begins de novo f now, the cam plates, Z and m, be adjusted, to, say, the positions shown in Fig. 2, the cam roller, j, is released when the inner plunger, 7), has completed only half its stroke, as shown in Fig. 2. The residual portion of the charge remains between the plungers owing to the pressure prevailing at the outlet port and is carried upwards, and eventually discharged through the inlet port when the plungers close or come together. As will be understood, therefore, by suitably regulating the period during which the outer plunger is held by its cams in stationary position, the volume of charge drawn in between the plungers and the volume of feed or discharge through the outlet port can be varied to suit different requirements, the regulation being effected by the adjustment of either or both of the cam plates, Z and W.

What I claim and desire to secure by Letters Patent is 1. A force pump comprising a cylinder having inlet and outlet ports, a pair of plungers reciprocable therein, means for retaining the upper or outer plunger station ary for a portion of the inward and downward strokes, and for moving the said plungers together for the remaining portions of the stroke so as to draw in a charge between the plunger-s, and expel it therefrom, the movement one plunger being effected by the movement of the other plunger, and means for varying the time in the cycle of operation. during which the upper or outer plunger is helm stationary, to vary the capacity o the pump.

A force pump as claimed in claim 1, wherein the rod of the inner or lower plunger extends through the upper or outer plunger, and is reciprocated by a crank shaft which carries a pair of adjustable cam plates having each a cam surface, designed to enand hold the upper or outer plunger. the inward and downward movements of which are effected by the inner plunger, and means for rotarily adjusting said cam plates with respect to each other and with respect to the cam shaft, to vary the capacity ofthe pump.

In a force pump, the combination with a cylinder having inlet and outlet ports, of a pair 'of plungers reciprocable therein, a crank shaft and crank connections from the crank to one of said plungers having a part extending through the other plunger and provided with means for engaging and moving the latter plunger in one direction, its movement in the opposite direction being effected by the crank actuated plunger, means operable in timed relation with the crank shaft for holding the second mentioned plunger stationary during portions of the reciprocating movements of the first mentioned plunger, means for varying the operative period of said holding means with respect to the crank shaft, to vary the capacity of the pump.

4. In a force pump, the combination with a cylinder having inlet and outlet ports, of a pair of plungers reciprocable therein, a

crank shaft and crank for operating both plungers, connections from said crank to one plunger, provided with a part extending through and having a sliding engagement with the other plunger and provided with means for positively operating the latter plunger in one direction, its movement in the opposite direction being effected by the crank actuated plunger, a pair of separate cams on the crank shaft provided with cam faces for holding the second mentioned plunger stationary during a portion of the reciprocating movements of the first mentioned plunger in both directions, a part connected with the second mentioned plunger for operatively engaging said cams, and means for adjusting said cams independently in a rotary direction with respect to the crank shaft, to vary the capacity of the pump.

5. In a force pump the combination with a cylinder, having inlet and outlet ports, or a pair of plungers reciprocable therein, a plunger rod connected to one of said plungers and extending through and having a sliding engagement with the other plunger, said rod having a part for engaging and moving the latter plunger, a crank shaft and crank, said crank being operatively connected to said plunger rod, a base plate carried by said shaft,independent cam plates provided with cams, a roller on the second mentioned plunger for engaging said cams to hold the plunger stationary during portions of the movement of the other plunger in both directions, and means for independently adjusting said cams with respect to and securing the same to said base plate.

6. In a force pump, the combination with a cylinder having inlet and outlet ports, of a pair of plungers reciprocable therein, a plunger rod connected to one of said plungers and extending through and having a sliding engagement with the other plunger, said rod having a part for engaging and moving the latter plunger, a crank shaft and crank a cross-head secured to said plunger rod and engaging a part connected with said crank, a rotary base plate carried by the crank shaft, a pair of cam plates each provided with a cam surface and having a slotted portion, bolts extending through said slotted portions and through the base plate for adjustably securing said cam plates to the base plate, and a friction roller connected with said second mentioned plunger for engaging said cams to hold the said plunger stationary during a portion of the movement of the first mentioned plunger in both directions.

MONTAGUE WVILLIAM TUTT'. 

